The Changing Face of Leverage

Move along, folks; not much to see here. That was broadly the message from Federal Reserve Chairwoman Janet Yellen on concerns about financial stability Wednesday. Investors should still take a closer look.

In particular, Ms. Yellen said she didn't see a "broad-based increase in leverage" that might be cause for concern. But there are a few ways to think about leverage, and reasons to worry about the way some markets are...